Iwlwifi

From Gentoo Linux Wiki

iwlwifi is Intel's open source driver for their newer wireless network adapters (Intel PRO/Wireless 3945ABG/BG and newer). The driver is included in the linux kernel since version 2.6.24.

Basis Setup

Kernel Setup

Enable the "mac80211" WLAN stack and crypto options for WEP, WPA and WPA2:

Networking --->
    [*] Networking support
        Wireless --->
            [*] Improved wireless configuration API
            [*] nl80211 new netlink interface support
            <*> Generic IEEE 802.11 Networking Stack (mac80211)
[*] Cryptographic API  --->
    --- Cryptographic API
    <*>   Cryptographic algorithm manager
    <*>   SHA1 digest algorithm
    <*>   SHA224 and SHA256 digest algorithm
    <*>   ECB support
    <*>   CBC support
    <*>   PCBC support
    <*>   AES cipher algorithms
    <*>   ARC4 cipher algorithm
    <*>   Michael MIC keyed digest algorithm

Then, be sure you have activated the option "Prompt for development and/or incomplete code/drivers" in the "General Setup" section of the kernel configuration:

General Setup --->
    [*] Prompt for development and/or incomplete code/drivers

Otherwise you won't be able to access the iwlwifi driver options in the kernel configuration!

Later on, you will also have to install the corresponding microcode file for your iwlwifi network adapter (it is, of course, available in portage). The iwlwifi driver loads this file at startup. To get this working, we need to enable the kernel's firmware_loader infrastructure:

Device Drivers --->
    Generic Driver Options --->
        [*] Userspace firmware loading support

IMPORTANT: For the next steps, it is highly recommended to compile the drivers as kernel modules (<M> instead of <*>). This is because the driver needs access to the file system (i.e. /lib/firmware) to load the firmware. If you compile the driver as built-in, it will not be able to load the (essential) firmware since the file systems are mounted *after* the kernel has been loaded.

Stable kernel (2.6.25)

If you have an Intel PRO/Wireless 3945AGB/BG Network Connection adapter, activate the iwl3945 driver:

Device Drivers --->
    [*] Network device support --->
        [*] Wireless LAN --->
            [*] Wireless LAN (IEEE 802.11)
            <M>   Intel PRO/Wireless 3945ABG/BG Network Connection
            [*]     Enable Wireless QoS in iwl3945 driver
            [*]     Enable Spectrum Measurement in iwl3945 drivers

Or if you have an Intel Wireless WiFi 4965AGN adapter, activate the iwl4965 driver:

Device Drivers --->
    [*] Network device support --->
        [*] Wireless LAN --->
            [*] Wireless LAN (IEEE 802.11)
            <M>   Intel Wireless WiFi 4965AGN
            [*]     Enable Wireless QoS in iwl4965 driver
            [*]       Enable 802.11n HT features in iwl4965 driver
            [*]     Enable Spectrum Measurement in iwl4965 driver
            [*]     Enable Sensitivity Calibration in iwl4965 driver

Unstable kernel (>=2.6.26)

If you have an Intel PRO/Wireless 3945AGB/BG Network Connection adapter, activate the iwl3945 driver:

Device Drivers --->
    [*] Network device support --->
        [*] Wireless LAN --->
            [*] Wireless LAN (IEEE 802.11)
            <*> Intel Wireless Wifi Core
            [*] IWLWIFI RF kill support
            < > Intel Wireless WiFi 4965AGN
            <M> Intel PRO/Wireless 3945ABG/BG Network Connection
            [*]   Enable Spectrum Measurement in iwl3945 drivers

Or if you have an Intel Wireless WiFi 4965AGN adapter, activate the iwl4965 driver:

Device Drivers --->
    [*] Network device support --->
        [*] Wireless LAN --->
            [*] Wireless LAN (IEEE 802.11)
            <*> Intel Wireless Wifi Core
            [*] IWLWIFI RF kill support
            <M> Intel Wireless WiFi 4965AGN
            [*]   Enable 802.11n HT features in iwl4965 driver
            [*]   Enable Spectrum Measurement in iwl4965 driver
            [*]   Enable Sensitivity Calibration in iwl4965 driver
            < > Intel PRO/Wireless 3945ABG/BG Network Connection

There is also now support for the WLAN LEDs, but be aware, that the LED blinks a lot when there is traffic:

Device Drivers --->
    [*] Network device support --->
        [*] Wireless LAN --->
            [*] Wireless LAN (IEEE 802.11)
            <M> Intel PRO/Wireless 3945ABG/BG Network Connection
            [*]   Enable LEDS features in iwl3945 driver

Software Setup - Installing the microcode files

As already said above, you have to install the corresponding firmware/microcode for your iwlwifi network device in order to become really useful as a wireless adapter.

Here is a short (and not complete) overview about what the microcode does, taken from the file README.iwlwifi-3945-ucode that is shipped with the microcode package iwl3945-ucode from portage:

To install the microcode, simply emerge iwl3945-ucode:

or, respectively iwl4965-ucode:

It is also recommended to check the README files of the microcode packages, as they contain other useful information for setting up the device. You can usually find them in /usr/share/doc/iwl3945-ucode-*/ or /usr/share/doc/iwl4965-ucode-*/ respectively, where * is to be replaced with the package version.

For further configuration follow the Gentoo Handbook.

TIP: For easy on-desktop configuration of your wireless adapter, see the NetworkManager HOWTO.

Advanced Topics

There are a few things you can play with through the sysfs interface /sys/bus/pci/drivers/iwl3945/00*/*

Monitor mode

To set your card into monitor mode, you need to patch the driver. See the guide at aircrack-ng.org.

Troubleshooting

• Switching from ipw3945

If you switched from ipw3945, you should unmerge everything that belonged to ipw3945. Also you may want to clean up your device names. Problems occur here because some drivers refer to your wireless interface as wlan0, some as ethX. You need to reconfigure /etc/udev/rules.d/70-persistent-net or recreate the rules there. You can use udevadm to recreate the rules #udevadm trigger --subsystem-match=net

• My WLAN LED does not work ?

Support is added since kernel 2.6.26.

• iwl4965: iwlwifi-4965-1.ucode firmware file req failed: Reason -2

This error indicate a firmware version/filename mismatch. Just rename the file to whatever iwlwifi displays in this case: iwlwifi-4965-1.ucode If this fails, try an alternate version, perhaps net-wireless/iwl4965-ucode-228.57.1.21.

• Problem with wpa_supplicant and asociation

If the AP SSID is hidden or there multiple SSIDs with the same name, be sure that ap_scan does not exist or is commented out in /etc/wpa_supplicant/wpa_supplicant.conf.

• Netmount starting too early

Netmount crapped out because the network was not ready. The solution, from this gentoo-user post is to edit /etc/conf.d/rc so that the Wifi is not started by udev, e.g., RC_PLUG_SERVICES="!net.wlan".